Engineering topics
Publications and source records attributed to Stolov, H. L..
Statistical evidence is presented that strongly suggests the existence of a real relationship between solar geomagnetic disturbance and the subsequent behavior of the 700-mbar contour height difference between 20 and 55 deg N. No acceptable physical mechanisms are as yet available to explain the observations.
The variation of the solar wind parameters (speed, magnetic field intensity, and proton density) and geomagnetic disturbance with location within the interplanetary sector structure is well established. The Kelvin-Helmholtz instability of the magnetopause provides a mechanism for the initiation of worldwide geomagnetic disturbance. Since the Kelvin-Helmholtz mechanism depends on an integration of several of the solar wind parameters, it was considered of interest to see how it varies within the sector structure. Support is given to the idea that the integration of the solar wind parameters via Kelvin-Helmholtz instability is an important concept in understanding geomagnetic disturbance.
Explorer 18 magnetometer and plasma probe data are used to calculate the magnitude of the Kelvin-Helmholtz instability criterion for 42 crossings of the magnetopause. The 30 crossings through the dipole field region show that for low levels of geomagnetic disturbance ( Kp less than or equal to 2) large regions of the magnetopause near the nose are stable, whereas for higher levels of geomagnetic disturbance (Kp greater than 2) only a small region near the nose is stable. The unstable regions are found further downstream. Similarly, the 12 crossings through the tail show that the unstable regions are downstream of the stable regions. The Kelvin-Helmholtz mechanism might be the 'viscous interaction' discussed by Axford and Hines (1961) and the relevant parameter for worldwide geomagnetic disturbance, just as the southward interplanetary field has been firmly established as the major relevant parameter in the case of substorm activity.
The Northern Hemisphere 700 mb contour heights from 20 N to 70 N for the period 1947-1970 are studied in conjunction with 272 key days, where the daily increase of the Ci index equals or exceeds 1.0. The superposed epoch method is applied from 33 days before to 66 days after the key day for a variety of zonal and meridional indices. It is shown that the 700 mb height difference between 20 N and 55 N increases significantly in winter 4 days following geomagnetic disturbance (in summer a less prominent but statistically significant increase is found 2 days earlier). The effect is most clear in winter in the quadrant 90-175 W and corresponds to a 7% increase in the mean geostrophic westerly flow. The statistical significance of the results is established by applying Student's t-test to the difference of each daily mean from the continuum.
Kelvin-Helmholtz instability at magnetopause, initiating semiannual variation of geomagnetic disturbances
Power spectra and cross spectra of surface pressure variations in polar regions compared to solar emission, noting Antarctic-Arctic relationship
Tropospheric periodic responses to chromospheric flares, analyzing stations atmospheric pressure power spectra
Polar cap ionospheric response to solar cosmic ray events observed by Mariners 2 and 4 solar proton measurements used to test magnetosphere models
Surface atmospheric pressures transient variations data analyzed during solar chromospheric flares suggesting no tropospheric responses to solar disturbances
Auroral absorption analysis during geomagnetic storm, noting satellite measurement of energetic particles
Geomagnetic activity variation with lunar phase, showing decrease several days before full Moon and increase several days after full Moon
Dipole field, magnetosphere, quiet day geomagnetic variations, dynamo theory for ionosphere origin, and other topics related to earth magnetic field
Geomagnetic field disturbance variations with lunar phase
Bifurcation of the outer van allen belt and related auroral phenomena